The present invention is directed to an improvement in an optical mouse, in particular, the device for transmitting light from the object surface to the sensing surface of an optical mouse.
The present application references the prior U.S. application Ser. No. 604,111 filed Apr. 16, 1984, assigned to the same assignee as the present applicant and the contents of which are incorporated herein by reference.
In that application an optical mouse was described wherein a device for transmitting light from an object surface to a sensing surface included a multiple element lens system or a fiber optic coupler.
In an optical lens system of that type, the field of view has the requirement of being about 8 mm in diameter with an image reduction of between 1:1 to 1:1.5 at the sensing surface. The multiple element design disclosed in the prior application must have an optical length of less than 0.75" to keep the mouse package small. In order to achieve the state requirements, the multiple element system to be utilized therein is relatively expensive given the overall cost of the optical mouse.
The prior application also suggested the use of fiber optic bundle.
While the use of a standard fiber optic bundle is operable, from the known technique of, for example, using two flexible coherent light pipes, this device also has the disadvantage of being too expensive in a mouse device since it necessitates passing light into one group of cores and removing the image from another group of cores and passing the light back to the sensing surface.